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821.
Behavioral and physiological responses to unpredictable changes in environmental conditions are, in part, mediated by glucocorticoids (corticosterone in birds). In polymorphic species, individuals of the same sex and age display different heritable melanin-based color morphs, associated with physiological and reproductive parameters and possibly alternative strategies to cope with variation in environmental conditions. We examined whether the role of corticosterone in resolving the trade-off between self-maintenance and reproductive activities covaries with the size of melanin-based spots displayed on the ventral body side of male barn owls. Administration of corticosterone to simulate physiological stress in males revealed pronounced changes in their food-provisioning rates to nestlings compared to control males. Corticosterone-treated males with small eumelanic spots reduced nestling provisioning rates as compared to controls, and also to a greater degree than did corticosterone-treated males with large spots. Large-spotted males generally exhibited lower parental provisioning and appear insensitive to exogenous corticosterone suggesting that the size of the black spots on the breast feathers predicts the ability to cope with stressful situations. The reduced provisioning rate of corticosterone-treated males caused a temporary reduction in nestling growth rates but, did not affect fledgling success. This suggests that moderately elevated corticosterone levels are not inhibitory to current reproduction but rather trigger behavioral responses to maximize lifetime reproductive success. 相似文献
822.
Schneider A Schuh A Maetzel FK Rückerl R Breitner S Peters A 《International journal of biometeorology》2008,52(6):549-547
Given the accumulating evidence that people with underlying heart disease are a particularly vulnerable group for triggers like changing meteorological parameters, the objective of this longitudinal study was to analyze the influence of weather parameters on blood pressure, arrhythmia and ischemia in cardiovascular patients. A panel study with repeated measurements was conducted in a rehabilitation clinic in Timmendorfer Strand (Baltic Sea, Germany) with 872 cardiovascular patients. Heart rate, blood pressure and electrocardiography changes were measured during repeated bicycle ergometries. Generalized Estimating Equations were used for regression analyses of immediate, delayed and cumulative influences of the daily measured meteorological data. For men, a decrease in air temperature and in water vapor pressure doubled the risk of ST-segment depression during ergometry [odds ratio (OR) for 1 day delay: 1.88 (1.24; 2.83) for air temperature] with a delay of 1-2 days. For women, an increase of their heart rate before the start of the ergometry [same day: 4.36 beats/min (0.99; 7.74) for air temperature] and a 2- to 3-fold higher risk for ventricular ectopic beats [1 day delay: OR 2.43 (1.17; 5.05) for air temperature] was observed with an increase in temperature and water vapor pressure in almost all analyzed time-windows. The study indicates that meteorological parameters can induce changes in heart function which may lead to adverse cardiovascular events especially in susceptible, diseased individuals. The observed effect on ST-segment depression could be a link between the association of weather changes and cardiovascular morbidity and mortality. 相似文献
823.
Regulation of plant cytosolic glyceraldehyde 3-phosphate dehydrogenase isoforms by thiol modifications 总被引:3,自引:0,他引:3
Holtgrefe S Gohlke J Starmann J Druce S Klocke S Altmann B Wojtera J Lindermayr C Scheibe R 《Physiologia plantarum》2008,133(2):211-228
Cytosolic NAD-dependent glyceraldehyde 3-P dehydrogenase (GAPDH; GapC; EC 1.2.1.12) catalyzes the oxidation of triose phosphates during glycolysis in all organisms, but additional functions of the protein has been put forward. Because of its reactive cysteine residue in the active site, it is susceptible to protein modification and oxidation. The addition of GSSG, and much more efficiently of S-nitrosoglutathione, was shown to inactivate the enzymes from Arabidopsis thaliana (isoforms GapC1 and 2), spinach, yeast and rabbit muscle. Inactivation was fully or at least partially reversible upon addition of DTT. The incorporation of glutathione upon formation of a mixed disulfide could be shown using biotinylated glutathione ethyl ester. Furthermore, using the biotin-switch assay, nitrosylated thiol groups could be shown to occur after treatment with nitric oxide donors. Using mass spectrometry and mutant proteins with one cysteine lacking, both cysteines (Cys-155 and Cys-159) were found to occur as glutathionylated and as nitrosylated forms. In preliminary experiments, it was shown that both GapC1 and GapC2 can bind to a partial gene sequence of the NADP-dependent malate dehydrogenase (EC 1.2.1.37; At5g58330). Transiently expressed GapC-green fluorescent protein fusion proteins were localized to the nucleus in A. thaliana protoplasts. As nuclear localization and DNA binding of GAPDH had been shown in numerous systems to occur upon stress, we assume that such mechanism might be part of the signaling pathway to induce increased malate-valve capacity and possibly other protective systems upon overreduction and initial formation of reactive oxygen and nitrogen species as well as to decrease and protect metabolism at the same time by modification of essential cysteine residues. 相似文献
824.
C(4) plants have up to 10-fold higher apparent CO(2) assimilation rates than the most productive C(3) plants. This requires higher fluxes of metabolic intermediates across the chloroplast envelope membranes of C(4) plants in comparison with those of C(3) plants. In particular, the fluxes of metabolites involved in the biochemical inorganic carbon pump of C(4) plants, such as malate, pyruvate, oxaloacetate, and phosphoenolpyruvate, must be considerably higher in C(4) plants because they exceed the apparent rate of photosynthetic CO(2) assimilation, whereas they represent relatively minor fluxes in C(3) plants. While the enzymatic steps involved in the C(4) biochemical inorganic carbon pump have been studied in much detail, little is known about the metabolite transporters in the envelope membranes of C(4) chloroplasts. In this study, we used comparative proteomics of chloroplast envelope membranes from the C(3) plant pea (Pisum sativum) and mesophyll cell chloroplast envelopes from the C(4) plant maize (Zea mays) to analyze the adaptation of the mesophyll cell chloroplast envelope proteome to the requirements of C(4) photosynthesis. We show that C(3)- and C(4)-type chloroplasts have qualitatively similar but quantitatively very different chloroplast envelope membrane proteomes. In particular, translocators involved in the transport of triosephosphate and phosphoenolpyruvate as well as two outer envelope porins are much more abundant in C(4) plants. Several putative transport proteins have been identified that are highly abundant in C(4) plants but relatively minor in C(3) envelopes. These represent prime candidates for the transport of C(4) photosynthetic intermediates, such as pyruvate, oxaloacetate, and malate. 相似文献
825.
Köhle Annegret Sommer Susanne Li Shu-Ming Schilde-Rentschler Lieselotte Ninnemann Helga Heide Lutz 《Molecular breeding : new strategies in plant improvement》2003,11(1):15-24
The bacterial gene ubiC encodes chorismate pyruvate-lyase (CPL), which converts chorismate to 4-hydroxybenzoate (4HB). The ubiC gene was expressed in tobacco (Nicotiana tabacum L., Solanaceae) and potato (Solanum tuberosum L., Solanaceae) under the control of the very strong constitutive plant promotor (ocs3) mas. High accumulation of 4HB glucosides as new, artificial secondary metabolites was observed in the transgenic plants. 4HB glucoside content reached 5.1% of dry weight in tobacco cell cultures and 4.0% of dry weight in the leaves of potato shoots. This is the highest content of an artificial secondary metabolite produced by genetic engineering of plants reported so far. Surprisingly, no growth retardation and no phenotypical changes were observed in the transgenic cell cultures and plants. Glucosylation of 4HB was achieved by endogeneous, constitutively expressed glucosyltransferases. The total amount of 4HB glucoside acccumulated showed a strict linear dependence on the expression level of ubiC. 相似文献
826.
Sphingolipids are key lipid regulators of cell viability: ceramide is one of the key molecules in inducing programmed cell death (apoptosis), whereas other sphingolipids, such as ceramide 1-phosphate, are mitogenic. The thermotropic and structural behavior of binary systems of N-hexadecanoyl-D-erythro-ceramide (C16-ceramide) or N-hexadecanoyl-D-erythro-ceramide-1-phosphate (C16-ceramide-1-phosphate; C16-C1P) with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) was studied with DSC and deuterium nuclear magnetic resonance (2H-NMR). Partial-phase diagrams (up to a mole fraction of sphingolipids X = 0.40) for both mixtures were constructed based on DSC and 2H-NMR observations. For C16-ceramide-containing bilayers DSC heating scans showed already at Xcer = 0.025 a complex structure of the main-phase transition peak suggestive of lateral-phase separation. The transition width increased significantly upon increasing Xcer, and the upper-phase boundary temperature of the mixture shifted to ∼65°C at Xcer = 0.40. The temperature range over which 2H-NMR spectra of C16-ceramide/DPPC-d62 mixtures displayed coexistence of gel and liquid crystalline domains increased from ∼10° for Xcer = 0.1 to ∼21° for Xcer = 0.4. For C16-C1P/DPPC mixtures, DSC and 2H-NMR observations indicated that two-phase coexistence was limited to significantly narrower temperature ranges for corresponding C1P concentrations. To complement these findings, C16-ceramide/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and C16-C1P/POPC mixtures were also studied by 2H-NMR and fluorescence techniques. These observations indicate that DPPC and POPC bilayers are significantly less perturbed by C16-C1P than by C16-ceramide and that C16-C1P is miscible within DPPC bilayers at least up to XC1P = 0.30. 相似文献
827.
Susanne Schlüter Charles M. A. P. Franz Frank Gesellchen Oliver Bertinetti Friedrich W. Herberg Friedrich R. J. Schmidt 《Current microbiology》2009,59(2):206-211
An Enterococcus faecalis mutant strain with a reduced ability for biofilm formation and primary attachment when compared to the high biofilm-forming
wild-type strain was characterized by molecular biological and proteomic approaches. A point mutation in the srt-1 gene, which encodes a sortase-type enzyme and is part of the recently described bee (biofilm enhancer in Enterococcus) gene cluster, could be identified in the mutant strain. The Srt-1 deficiency resulted in a loss of the Bee-2 protein within
a high molecular weight complex in cell surface protein extracts, as determined by mass spectrometry. These findings strongly
suggest a specific linkage of Bee-2 to Bee-1 and Bee-3 within a complex by Srt-1. Furthermore, the identification of specific
pilin motifs conserved in surface proteins of gram-positive bacteria indicated a possible involvement of the bee genes in the formation of pili structures, and may thus play a role in enhancing biofilm formation in Enterococcus faecalis. 相似文献
828.
Susanne Awe Annett Mikolasch Frieder Schauer 《Applied microbiology and biotechnology》2009,84(5):965-976
In this study, we investigated the ability of the yeast Trichosporon asahii SBUG-Y 833 to assimilate phenylalkanes with alkyl chain lengths from 7 to 12 carbon atoms, and we describe for the first time the formation of coumarines via a novel degradation pathway other than the normal terminal and ß-oxidation pathway of the alkyl residues. Besides benzoic acid and its further oxidation products, six new metabolites were identified. These were the three coumarines—4-hydroxycoumarin, 4,6-dihydroxycoumarin, 4,8-dihydroxycoumarin—and the three alkyl substituted aromatic acids—7-phenylheptanoic acid, 2-hydroxyphenylheptanoic acid, and 2-hydroxyphenylpropanoic acid. 4-Hydroxycoumarin was the main extracellular metabolite during the degradation of both odd- and even-chain phenylalkanes and was also produced during further biotransformation of 2-hydroxyphenylpropanoic acid and trans-2-hydroxycinnamic acid. Due to the ability of T. asahii to form hydroxylated coumarines, the transformation of 7-hydroxycoumarin and 2,4-dihydroxyphenylpropanoic acid was investigated. Yeast cells supplemented with 7-hydroxycoumarin formed 6,7-dihydroxycoumarin and 4,7-dihydroxycoumarin. The transformation of 2,4-dihydroxyphenylpropanoic acid yielded to 4,7-dihydroxycoumarin as the main product. All hydroxylated coumarines were continuously accumulated and are very resistant to further oxidation. The high potential of the yeast T. asahii SBUG-Y 833 to form different hydroxylated coumarines from alkylaromatics suggests possible applications in the biotechnological production of coumarine structures with medical potential as anticoagulative and antitumor pharmaceutical. 相似文献
829.
830.
Alvaro Peix Elke Lang Susanne Verbarg Cathrin Spröer Raúl Rivas Ignacio Santa-Regina Pedro F. Mateos Eustoquio Martínez-Molina Claudino Rodríguez-Barrueco Encarna Velázquez 《Systematic and applied microbiology》2009
During a screening of phosphate solubilizing bacteria (PSB) in agricultural soils, two strains, IH9 and OCI1, were isolated from the rhizosphere of grasses in Spain, and they showed a high ability to solubilize phosphate in vitro. Inoculation experiments in chickpea and barley were conducted with both strains and the results demonstrated their ability to promote plant growth. The 16S rRNA gene sequences of these strains were nearly identical to each other and to those of Acinetobacter calcoaceticus DSM 30006T, as well as the strain CIP 70.29 representing genomospecies 3. Their phenotypic characteristics also coincided with those of strains forming the A. calcoaceticus–baumannii complex. They differed from A. calcoaceticus in the utilization of l-tartrate as a carbon source and from genomospecies 3 in the use of d-asparagine as a carbon source. The 16S–23S intergenic spacer (ITS) sequences of the two isolates showed nearly 98% identities to those of A. calcoaceticus, confirming that they belong to this phylogenetic group. However, the isolates appeared as a separate branch from the A. calcoaceticus sequences, indicating their molecular separation from other A. calcoaceticus strains. The analysis of three housekeeping genes, recA, rpoD and gyrB, confirmed that IH9 and OCI1 form a distinct lineage within A. calcoaceticus. These results were congruent with those from DNA–DNA hybridization, indicating that strains IH9 and OCI1 constitute a new genomovar for which we propose the name A. calcoaceticus genomovar rhizosphaerae. 相似文献